A BEECH 1900D IN CLB AT 8000 FT DECLARED AN EMER AND DIVERTED DUE TO FORWARD PAX DOOR OPENING.

Narrative

SHORTLY AFTER TKOF FROM RWY 17L AT ZZZ; DURING THE CLBOUT; WE GOT THE 'CABIN DOOR' ANNUNCIATOR. AT THAT TIME WE COMMENCED THE MEMORY ITEMS FOR A CABIN DOOR ANNUNCIATOR. WE THEN MADE THE DECISION TO RETURN TO ZZZ AND LAND. WE INFORMED ATC THAT WE NEEDED TO RETURN. AS WE STARTED THE TURN TO THE E; WE HEARD A LOUD BANG; AND OBSERVED THAT THE AIRSTAIR DOOR HAD OPENED. I TURNED TO MAKE SURE WE HADN'T LOST ANY PAX AND THAT EVERYONE WAS OK. SINCE THERE WAS SO MUCH NOISE IN THE CABIN; WE COMMUNICATED AS BEST WE COULD; DECLARED AN EMER; AND RETURNED FOR A LNDG ON RWY 26. AFTER LNDG; I SECURED THE ACFT; MADE SURE THE PAX WERE OK; THEN CONTACTED DISPATCH TO INFORM THEM OF THE SIT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE FO CLOSED THE DOOR AT DEP TIME AND VERIFIED THE ROTARY LOCKS WERE ENGAGED WITH LOCK STRIPES ALIGNED AND THE COCKPIT DOOR WARNING LIGHT WAS OUT. THE RPTR SAID THE ACFT DOOR WARNING LIGHT CAME ON AT ABOUT 8000 FT AND WHILE IN A L BANK TO RETURN TO THE FIELD THE DOOR OPENED WITH A LOUD BANG. THE RPTR STATED AN EMER WAS DECLARED AND IT WAS NOTED THE MASSIVE AIRFLOW DISRUPTION AROUND THE DOOR WHICH WAS NOW POSITIONED 8 INCHES FROM THE L PROP. THE RPTR SAID ON LNDG IT WAS DISCOVERED THE AFT DOOR CABLE BROKE AND WAS INGESTED BY THE PROP WHICH WAS DAMAGED. THE RPTR STATED THE COMPANY AND FLT MGRS WILL NOT ADVISE THE CREW OF THE MODE OF FAILURE AND ARE EXTREMELY CLOSE MOUTHED ABOUT THE INCIDENT. THE RPTR SAID A FRIEND ADVISED HIM OF A SIMILAR INCIDENT IN THE NORTHERN UNITED STATES; BUT COULD GIVE NO DATE OR DETAILS OF THE FINDINGS. THE RPTR STATED THE FAA SCHEDULED A HEARING ATTENDED BY THE FLT CREW AND AFTER ALL THE FACTS WERE PRESENTED THE CREW WAS RELIEVED OF ANY RESPONSIBILITY FOR THE INCIDENT. THE RPTR SAID THE COMPANY HEARING WAS HELD THE NEXT DAY AND THE FLT CREW WAS SENT BACK TO WORK BUT STILL NO DETAILS ON THE DOOR FAILURE. THE RPTR STATED IN REVIEWING A LOGBOOK PRIOR TO FLT A DOOR RPT WAS FOUND ON LCL MAINT RPTED THE FAA WAS OUT CHKING DOORS. THE RPTR SAID IN CONTACTING THE LCL FLT STANDARDS OFFICE TO DETERMINE THEIR FINDINGS THE SAFETY INSPECTOR ADVISED 2 OUT OF EVERY 4 AIRPLANES HAD DOORS THAT COULD BE FALSE LATCHED.